Why should you care who services your mortgage?
The only thing on your mind should be proper treatment of any payments you make exceeding your standard payment. You need to be sure that extra amounts are credited to principal.
That's probably a rhetorical question, but I'll bite. Game theory applied to evolutionary biology provides a compelling qualitative answer to this question. You can read about it in Richard Dawkins' "Selfish Gene".
Basically, if social interaction is regarded as an Iterated Prisoner's Dilemma, with options to cooperate or defect at each turn, one might say that a society cannot prosper if everyone always defects, but also that a society made up exclusively of cooperators provides an advantage to genetic mutations that give rise to defector behavior. Societies will therefore tend to have a some degree of cooperation with some freeloading from defectors, and the balance will fluctuate.